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Re: [TCML] how is this possible?
Hi Norman,
Great report! Thanks for sharing it with the list. I don't expect TCML members will be lining up to demand photographic proof of your claims. Your result is unusual, but entirely possible. I can offer a number of possible explanations.
Most likely cause is mains resonance. I believe 37nF is the mains resonant value for 9/60, very close to your 30nF cap. Mains resonance allows an NST to exceed its faceplate value. I once resonated a 15/30 NST with a 6nF cap, and got it to jump a 3" spark gap! I didn't understand what a bad thing I was doing to my brand-new NST (Transco PolyLock). Fortunately, I didn't ruin my NST. Anyhow, your NST may be providing lots more voltage & current than you expect. Put that together with a spark gap that's set a little too wide, and you get bigger than expected sparks. Be aware that mains resonance can shorten the life of an NST.
Along with mains resonance, you may have achieved optimal coupling between the TC primary and secondary. You may have also hit upon an optimal size & elevation for your toroid. Your spark gap may be quenching at an optimal spot on the envelope. In other words, your big sparks may be due to 60Hz resonance, accidental coil optimization, or both.
Congrats on the big sparks. Have fun with it.
Greg
--- On Sat, 2/20/10, Norman Stepp <ndsteppii@xxxxxxxxx> wrote:
> From: Norman Stepp <ndsteppii@xxxxxxxxx>
> Subject: [TCML] how is this possible?
> To: tesla@xxxxxxxxxx
> Date: Saturday, February 20, 2010, 1:17 AM
> Using my un-altered 9/60 w/ no variac
> or anything special a friend and myself (God strike me dead
> where I sit) achieved 41.5" arcs to a grounded ladder. this
> is 1.5" more than the max using the john f. formula. the
> coil specs are as follows: franceformer 9/60 static gap w/
> computer fan, 6" coil diameter, 24" coil length, 1289 turns
> of 26 awg heavy build. toroid is 17 inches,
> I am on turn 14 of the primary. Cap is Maxwell 35kv DC
> 30nF pulse cap.
> No PFC, and breakout is tungsten welding rod pushed into
> toroid with a brass drawer knob on the very end. the
> measurement was from tip of breakout to ladder. two
> witnesseses present when it happend, can reproduce it w/
> proof if nessary.this wasn't one rouge hit it was several,
> what is going on here? any questions or answers?
>
>
>
>
>
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